A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the paras...A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the parasitic effectively and enables self-oscillation frequency enhancement. Besides, bandwidth enhancement techniques based on a center-tap capacitor in input balun design and inductive peaking in latch design are adopted to improve further high frequency performance with low power consumption. As a proof of concept, design of a divide-by-2 static frequency divider in 0.13 μm SiGe BiCMOS technology is reported. With single-ended input clock signal, the divider is measured to be operated from 40 to 90 GHz. Phase noise measurements of a 90 GHz input clock signal indicate ideal behavior with no measurable noise contribution from the divider. The divider followed by a buffer that can deliver more than-10 dBm output power, which is sufficient to drive succeeding stage. To the author's knowledge, the divider exhibits a competitive power dissipation and the highest FOM among silicon based frequency dividers that operating higher than 70 GHz.展开更多
Formation of negative static charges (e-) throughout troposphere is a natural phenomenon revealed by some weather events such as storms and lightning flashes that accompany thunderclouds. This climatic phenomenon (for...Formation of negative static charges (e-) throughout troposphere is a natural phenomenon revealed by some weather events such as storms and lightning flashes that accompany thunderclouds. This climatic phenomenon (formation of negative charge in that case) has long been considered as physical phenomena of very small space-time scales. Now we have good reasons to say that this perception of troposphere electrical status is totally meaningless. Indeed, it is now easy to show that significant numbers of electrons are provided to troposphere at each appearance of a thunderstorm (or a lightning flash). Thereafter, movement implemented in the troposphere by winds (e.g., West African aerojet) contributes to the formation of low altitudes Electrojets (e.g., West African Equatorial Aerojet gives birth to West African Equatorial Electrojet). The existence of Low Layers Equatorial Electrojets (LL-EEJ) was totally unknown by the first theorists who have studied the Earth’s Ionosphere Plasma Physics and Electrodynamics. This mistake has led their followers to many questions unanswered in their attempt to explain the longitudinal and seasonal variations of observed EEJ. In this paper, we will provide many useful explanations on the manner in which clouds provide oxygen to troposphere and thereafter trigger negative static charges (e-) throughout both troposphere and ionosphere. Indeed, this paper also explains how, opportunely, the ITF (inter tropical front) plays the role of the tap which facilitates oxygen transfer from troposphere to ionosphere. Detailed studies on the Earth’s troposphere plasma physics and electrodynamics are impatiently awaited.展开更多
This paper describes scientific research conducted to highlight the potential of an integrated GPR-UAV system in engineering-geological applications.The analysis focused on the stability of a natural scree slope in th...This paper describes scientific research conducted to highlight the potential of an integrated GPR-UAV system in engineering-geological applications.The analysis focused on the stability of a natural scree slope in the Germanasca Valley,in the western Italian Alps.As a consequence of its steep shape and the related geological hazard,the study used different remote sensed methodologies such as UAV photogrammetry and geophysics survey by a GPR-drone integrated system.Furthermore,conventional in-situ surveys led to the collection of geological and geomorphological data.The use of the UAV-mounted GPR allowed us to investigate the bedrock depth under the detrital slope deposit,using a non-invasive technique able to conduct surveys on inaccessible areas prone to hazardous conditions for operators.The collected evidence and the results of the analysis highlighted the stability of the slope with Factors of Safety,verified in static conditions(i.e.,natural static condition and static condition with snow cover),slightly above the stability limit value of 1.On the contrary,the dynamic loading conditions(i.e.,seismic action applied)showed a Factor of Safety below the stability limit value.The UAV-mounted GPR represented an essential contribution to the surveys allowing the definition of the interface debris deposit-bedrock,which are useful to design the slope model and to evaluate the scree slope stability in different conditions.展开更多
基金supported by National Natural Science Foundation of China under Grant 61701114the National Science and Technology Major Project under Grant 2017ZX03001020the Scientific Research Foundation of Graduate School of Southeast University (Grant No. YBJJ1811)
文摘A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the parasitic effectively and enables self-oscillation frequency enhancement. Besides, bandwidth enhancement techniques based on a center-tap capacitor in input balun design and inductive peaking in latch design are adopted to improve further high frequency performance with low power consumption. As a proof of concept, design of a divide-by-2 static frequency divider in 0.13 μm SiGe BiCMOS technology is reported. With single-ended input clock signal, the divider is measured to be operated from 40 to 90 GHz. Phase noise measurements of a 90 GHz input clock signal indicate ideal behavior with no measurable noise contribution from the divider. The divider followed by a buffer that can deliver more than-10 dBm output power, which is sufficient to drive succeeding stage. To the author's knowledge, the divider exhibits a competitive power dissipation and the highest FOM among silicon based frequency dividers that operating higher than 70 GHz.
文摘Formation of negative static charges (e-) throughout troposphere is a natural phenomenon revealed by some weather events such as storms and lightning flashes that accompany thunderclouds. This climatic phenomenon (formation of negative charge in that case) has long been considered as physical phenomena of very small space-time scales. Now we have good reasons to say that this perception of troposphere electrical status is totally meaningless. Indeed, it is now easy to show that significant numbers of electrons are provided to troposphere at each appearance of a thunderstorm (or a lightning flash). Thereafter, movement implemented in the troposphere by winds (e.g., West African aerojet) contributes to the formation of low altitudes Electrojets (e.g., West African Equatorial Aerojet gives birth to West African Equatorial Electrojet). The existence of Low Layers Equatorial Electrojets (LL-EEJ) was totally unknown by the first theorists who have studied the Earth’s Ionosphere Plasma Physics and Electrodynamics. This mistake has led their followers to many questions unanswered in their attempt to explain the longitudinal and seasonal variations of observed EEJ. In this paper, we will provide many useful explanations on the manner in which clouds provide oxygen to troposphere and thereafter trigger negative static charges (e-) throughout both troposphere and ionosphere. Indeed, this paper also explains how, opportunely, the ITF (inter tropical front) plays the role of the tap which facilitates oxygen transfer from troposphere to ionosphere. Detailed studies on the Earth’s troposphere plasma physics and electrodynamics are impatiently awaited.
文摘This paper describes scientific research conducted to highlight the potential of an integrated GPR-UAV system in engineering-geological applications.The analysis focused on the stability of a natural scree slope in the Germanasca Valley,in the western Italian Alps.As a consequence of its steep shape and the related geological hazard,the study used different remote sensed methodologies such as UAV photogrammetry and geophysics survey by a GPR-drone integrated system.Furthermore,conventional in-situ surveys led to the collection of geological and geomorphological data.The use of the UAV-mounted GPR allowed us to investigate the bedrock depth under the detrital slope deposit,using a non-invasive technique able to conduct surveys on inaccessible areas prone to hazardous conditions for operators.The collected evidence and the results of the analysis highlighted the stability of the slope with Factors of Safety,verified in static conditions(i.e.,natural static condition and static condition with snow cover),slightly above the stability limit value of 1.On the contrary,the dynamic loading conditions(i.e.,seismic action applied)showed a Factor of Safety below the stability limit value.The UAV-mounted GPR represented an essential contribution to the surveys allowing the definition of the interface debris deposit-bedrock,which are useful to design the slope model and to evaluate the scree slope stability in different conditions.
